1. Field of the Invention:
The present invention is directed to an improvement of an air cleaner of an engine for a vehicle.
2. Description of the Prior Art:
An engine mounted on a vehicle is typically equipped with an air cleaner for cleaning the air sucked.
The great majority of such air cleaners are each provided with a hot air intake mechanism for sucking the air warmed up by an exhaust manifold in the cold atmosphere. One typical structure of these conventional air cleaners will be described with reference to FIGS. 4 through 6. FIG. 4 is a plan view of the air cleaner. The numeral 1 designates the air cleaner. A duct-like air intake unit 2 is intended to suck in the air which will in turn be fed to air cleaner 1. The numeral 3 represents a known air valve for effecting change-over of suction passageways between the warmed air and the atmosphere. The air valve is linked to the air intake unit. The linkage therebetween involves a variety of fashions in terms of a structure of a case of the air cleaner. The air cleaner case is composed of an upper and lower cases which are fitted together; and commonly the air intake unit is also formed integrally therewith. The fitting portion between the upper and lower cases undergoes airtight processing in order to keep the airtightness of an air passageway of the air cleaner. On the other hand, an outlet tube of the air valve assumes a cylindrical configuration, and it is required that the fitting portion be formed to take the cylindrical shape adaptive to the fitting in the air suction passageway for keeping the airtightness. For this reason, the end of air intake unit is, as a matter of fact, formed to assume the cylindrical shape. In this case, parts other than the cylindrical top of the air intake unit are shaped generally by fitting the upper and lower cases together, and hence the maintaining of the airtightness entails a special structure in the joining portion. This kind of special structure will be explained in conjunction wit FIGS. 5 and 6.
Turning first to FIG. 5, a lower case 4 fringe close to warm air valve 3 is partially swollen (referred to as a swelling 9), while upper case 5 assumes a configuration corresponding to swelling 9. In this manner, lower case 4 is formed with swelling 9, whereby upper and lower cases 5 and 4 can be airtightly fitted to each other.
Referring next to FIG. 6, a lower case 4 fringe positioned closely just under air valve 3 is recessed (referred to as a recess 10), while upper case 5 assumes a configuration corresponding to recess 10. Upper and lower cases 5 and 4 can be airtightly fitted to each other. Note that in FIGS. 5 and 6 the numeral 11 designates a valve body of air valve 3, the numeral 12 represents an air hose, and 13 indicates a cylinder head.
The structure depicted in FIG. 5, however, presents a problem in which there is shaped a portion a whose interior area is sharply enlarged in the middle of the air intake unit, and the air stagnates in portion a to cause disturbance of an air flow, resulting in generation of sucking sounds. Whereas in the structure of FIG. 6, the middle of the air intake unit is formed with a portion a' the interior area of which is sharply narrowed. As a result, there arise such problems that a suction resistance augments in portion a', which in turn tends to cause a drop in output of the engine and the generation of the sucking sounds.
Both of the structures depicted in FIG. 5 and 6 have disadvantages in terms of layout of the engine and a suction efficiency of hot air, because there increase a positional height of air valve and an engine overall height H as well, and additionally a length of arranged air hose 12 becomes large.
Accordingly, it is a primary object of the present invention to provide an air cleaner for a vehicle which obviates the above-described defects.
It is another object of the present invention to provide an improved air cleaner arranged such that an engine overall height is reduced.